Television replay reshaped the landscape of American sports. As the technology evolved, replay continually changed the way games were broadcast, analyzed, officiated and, most of all, viewed by the sports public. The godfather of it all was the late Roone Arledge, who while at ABC constantly pushed for innovative ways to bring the drama of sports to the TV screen. In 1994, Sports Illustrated ranked Arledge third, behind only Muhammad Ali and Michael Jordan, in its 40th anniversary issue, honoring the 40 most significant individuals in U.S. sports since SI was first published. Following is a look at key technological milestones in the history of replay and televised sports:

The first attempt

George Retzlaff, a Toronto-based producer for the Canadian Broadcasting Corporation's "Hockey Night in Canada," in 1955 used a processor that developed film in 30 seconds. It led to a "wet film" (kinescope) replay of one goal in one game that was aired several minutes after the live play. It was not "instant replay" as we know it today, and Retzlaff's idea failed to take hold.

Slow-motion replay

In 1961, the 29-year-old Arledge asked ABC engineer Bob Trachinger if it would be possible to replay a piece of sports videotape in slow motion. Trachinger came up with delayed videotape replay, which was first tested during a Texas-Texas A&M college football game. But slow-motion replay's first widespread use came Nov. 25, 1961, during ABC's broadcast of a Boston College-Syracuse football game. Jack Concannon, Boston College's quarterback, made a spectacular, 70-yard scoring run.

The Hawk-Eye system began in 2001 and became part of tennis' tiebreaking system within a few years. (Getty Images file)

Curt Gowdy called the play live, and his color analyst, Paul Christman, reviewed the play in slow motion at halftime. Arledge later boasted that the moment "would change TV sports forever."

First "instant" replay

Tony Verna, a director at CBS, invented the first instant replay as we have come to know it. He developed a system — using audio tones added to the cue track of the videotape — that enabled him to rewind to the point just before the ball was snapped. Verna's invention debuted Dec. 7, 1963, during the annual Army-Navy football game in Philadelphia. He was able to get one replay to work that day, a 1-yard scoring run by Army quarterback Rollie Stichweh in the fourth quarter. According to Verna, the first replay tape, which has since been lost, was recorded over a tape that included episodes of "I Love Lucy."

Instant slow-mo

The Ampex company unveiled a high-band, color-disc video machine for instant replay that greatly enhanced the technology. ABC first used the new machine in April 1967 for instant, slow-motion playback of downhill skiing at the World Series of Skiing. It was the first use of immediate, instant slow-motion replay during a live sports event.

CBS chalkboard

The Chicago-based Interand Corp. produced an electronic stylus, connected to a special monitor, that allowed commentators to draw freehand over television pictures. CBS's John Madden embraced the new technology during the Giants-49ers NFC divisional playoff game Jan. 3, 1982, offering insight into the game that viewers had never gotten before. Madden became adept at showing viewers such things as how zone defenses worked, how plays developed and which players completed or blew their assignments. TV coverage of the NFL was changed forever.

Instant replay has become almost as much a part of the NFL as helmets. (Getty Images file)

Bird's-eye view

The Hawk-Eye system, which is now used at all major tennis events, was the creation of a 26-year-old British mathematician/computer expert named Paul Hawkins. In 2001, he presented a replay system that used several high-speed cameras that tracked visual data into a computer. The computer then reproduced the ball's flight path and pinpointed its landing spot, all within a margin of error of only 3.6 millimeters. Though it was first used in cricket, Hawk-Eye found its way into the booth of TV tennis analysts in 2002. Hawk-Eye made its official tour debut with an eight-camera system March 23, 2006. In March 2008, the International Tennis Federation collaborated with the men's and women's tours to declare a uniform standard: three unsuccessful challenges per set, plus an additional challenge in a tiebreaker. Anytime a player was proved correct, he or she would retain that challenge.

Baseball's K zone

On a July 1, 2001, telecast of "Sunday Night Baseball," ESPN debuted the K Zone, a computer-generated, on-screen graphic that tracked pitches to the plate. Calibrated specifically for each batter, it showed the speed and the location in which the ball crossed the hitter's strike zone. Soon after, Fox broadcasts beginning using Fox Trax and TBS introduced Pitch Trax.

NBA buzzer-beaters

After a number of controversial calls during the 2001 playoffs, the NBA began using instant replay in 2002 to determine whether shots were released before time expired. At the same time, the NBA also mandated the installation of light strips on both the backboard and the scorer's table that lit up when time expired. The lights help officials when they review a play.

Hi-def refs

In 2007, the NFL installed high-definition monitors for officials to use to review plays on the field. It marked the first major upgrade in technology since the NFL's replay challenge system was installed in 1999.

NFL's "Matrix"

In its 2013 inaugural telecast of "Sunday Night Football" between the San Francisco 49ers and Dallas Cowboys at AT&T Stadium, NBC Sports debuted its 360-degree instant replays, using so-called freeD technology developed by Replay Technologies. The system consisted of 24 cameras — two sets of 12 cameras set up at opposite ends of the field — that allowed color commentator Cris Collinsworth to show replays in the red zone from every possible camera angle. Collinsworth was able to rotate the camera's view around the action, as was done in the movie "The Matrix."

Candid cameras

Fox Sports coverage of the 2013 World Series between the Boston Red Sox and St. Louis Cardinals included 29 high-definition cameras, including handheld, wireless and robotic devices. Fox's innovative "Diamond Cam" sat just off the ground on the grass near home plate, looking back at the catcher.

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